Plant growth and flowering in phlox as influenced by different levels of BA and pinching

Introduction

Annuals are the group of plants which complete their life cycle in one season or in a year (Singh and Sisodia, 2017) [12] . Phlox (Phlox drummondii) is grown both as an annual and perennial plant in the garden. It belongs to the family Polemoniaceae. It is also known as star flower. It is native to the United States of America especially in the region of Texas. One of the most popular and favourite annuals are grown for its brilliant display and long-lasting blooming period. It is easy to cultivation, free flowering and ranges in height from 5 to 45 cm. The large flowered phloxes are excellent for beds, border and as cut flowers. The compact ones are grown in the window boxes, pot, formal beds and also in edgings. It is also suitable for rock garden and dry walls. Benzyladenine (BA) is recognized by its ability to induce cell division in certain plant tissues. it can also overcome the apical dominance of many plants and stimulate the lateral buds to develop into an entire new plant. BA can delay senescence and cause transport of many solutes from older parts of the leaves or even from older leaves into the treated zone. The influence of benzyl adenine (BA) on flowering varies on the species to species and found beneficial in growth and flowering in calendula and California poppy (Singh, 2003 and Singh, 2005) [10,11] . Apical dominance is one of the major constraints in annual flower crop especially dianthus which hinder the plant from profuse branching and flowering thus pinching is a best approach to increase lateral branches and eventually number of flowers. When the terminal portion of the shoots is clipped early, side branches develop earlier, resulting in a greater number of flowers of superior quality and uniform size (Singh and Sisodia, 2017) [12] .

Materials and Methods

The experiment was conducted at Horticultural Research Farm, Department of Horticulture, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India. Seeds of phlox were sown in a raised nursery bed and after one month the seedlings were transplanted in 6×3 m plots with row to row spacing of 60 cm and plant to plant spacing of 50 cm. Treatments were given with concentrations of BA at 50, 100, 150, 200, 250 and 300ppm at 23 days after transplanting and also single pinching was done at 30 days after transplanting. The experiment was carried out in a Randomized Block Design with three replications. All the package of practices were followed as per recommendation to raise a quality crop. Five plants were selected randomly from each treatment per replication and the observations were recorded on various growth and flowering parameters on these plants. The data was statistically analyzed using analysis of variance.

Results and Discussion

Effect of pinching on growth attributes

The study revealed that the growth parameter viz., plant height, number of branches per plant, leaf area and plant spread were significantly influenced by the application of pinching (Table 1). According to ANOVA analysis, when compared to non-pinching, pinching at 30 days reduced plant height (34.04 cm), maximum number of primary branches/plant (11.97), leaf area (49.91cm 2 ) and plant spread at 90 days (49.89 cm). Conspicuous effect due to pinching was might be due to increased stem length on which maximum number of branches were developed which resulted into more lateral branches and maximum number of flowers and yield increased. These resulted conformities with the finding of Chauhan et al. (2005) [4] , Singh et al. (2015) [15] in marigold, Kumar et al. (2011) [8] and Fatma (2017) [6] in calendula.

Effect of BA on growth attributes

The obtained results (Tables 1) revealed that application of benzyl adenine at 200 and 300 ppm created significant stimulative effects on growth parameters of phlox. These effects were clear with the resulted induced increases in plant height, number of primary branches, leaf area and plant spread. Maximum plant height (38.23 cm), primary branches at 90 days/plant (13.42) and plant spread at 90 days (53.75 cm)was observed with BA200 ppm. However, maximum leaf area (58.21cm 2 ) was recorded with application of BA at 300 ppm. This increase in plant height and plant spread due to the role of the BA in cell elongation and division. its lead to increase the nitrogen content on leaves which is important in the formation of protein, nucleic acid, chlorophyll, enzyme, vitamins and plant hormones. In addition to the formation of cell membrane, ATP and NADP and amides. Maximum plant height and plants spread with application of BA has been noticed in lily (Naji et al., 2015) [9] and in chrysanthemum (Singh and Bala., 2018) [18] .

Interaction effect

The effect of interaction between application of BA and pinching was found to be significant (Table 1). Significantly maximum number of primary branches at 90 days/plant(14.33) was found with pinching × BA 200 ppm which was at par with pinching × BA 50 ppm. The improvement in various growth characteristics is most likely due to the physiological action of BA, which increased the number and size of meristematic tissue cells and along with this pinching breaks the apical dominance enhancing lateral growth which resulted in maximum number of primary branches leading to more accumulation of biomass. Maximum plant height at 90 DAT (46.78 cm) was observed with interaction of no pinching × BA 200 ppm. Maximum leaf area (63.97cm 2 )and spread (54.25 cm) was also noted in interaction of pinching × BA 200 ppm. The interaction effect of growth regulator with pinching had a positive influence on growth attributing characters in marigold (Badge et al., 2015) [3] .

Effect of pinching on flowering attributes

All the flowering characteristics are significantly influenced by pinching except dry weight of flower (Table 2). Statistically, minimum days to bud initiation (69.14 days), flowering (80.79 days) and maximum days to flower withering (89.06 days) were seen with no pinching. However, maximum bud diameter (19.97 cm) was recorded with pinching at 30 DAT. Similarly, maximum number of flowers per plant (241.25), fresh (1.19 g) and dry weight of flower (0.189 g) were obtained with pinching at 30 DAT. This was due to superior growth obtained in pinched plants, which was responsible for the production of bigger flowers, a greater number of flowers and, as a result, more flower weight in pinching. These results are in close agreement with the findings of Singh et al. (2018) [13] , Singh et al. (2017) [14] in marigold, Singh and Baboo (2003) [16] in chrysanthemum and Gaidhani et al. (2020) [7] in china aster.

Effect of BA on flowering attributes

All the flowering attributes were significantly influenced due to various levels of BA in phlox (Table 2). Significantly, minimum days to bud initiation (66.75 days), flowering (79.75 days), fresh weight of flower (1.76 g), dry weight of flower (0.24 g) and flower diameter (20.48 cm) were recorded with BA 150 ppm. Application of BA 200 ppm resulted maximum number of flower and longevity of flowers (90.69 days). These increases in flowering attributes by application of BA might be due to the enhanced cell division, cell elongation and improved translocation of metabolites to the flowers. These findings are corroborated with the results of Asil et al. (2011) [2] in tuberose, Shoura (2018) in rose and Singh et al. (2018) [17] in lily.

Interaction effect

The effect of interaction between BA and pinching was found to be significant (Table 2). Earliest bud initiation (66.33 days) and flowering (77.50 days) were noticed with the interaction of BA 50 ppm ×nopinching. Significantly, maximum flower diameter (21.28 cm), fresh weight of flower (2.30 g), dry weight of flower (0.26 g) and flower withering (92.00 days) were recorded with interaction of BA 150 ppm × pinching. Maximum number of flower (268.33) was observed with the interaction of BA 300 ppm × pinching. Similar trend of results was reported by Badge et al. (2015) [3] , Singh et al. (2017) [14] in marigold and Ali et al. (2021) [1] in zinnia.

Conclusion

Above the findings summarized above it was concluded that BA 200 ppm combined with pinching showed increased vegetative growth and BA 150 ppm with pinching had significant influenced on flower yield in phlox.

References

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